Transmission1

Bogget wrote:And i quote:-
"In conventional FM two-way radio systems, the most common form of selective calling is CTCSS, which is based on a sub-audible tone. One implementation of this system is by Motorola and is called Private Line, or PL. Radios made by nearly any manufacturer will work acceptably with existing systems using CTCSS. The system allows groups of radios to remain muted while other users are talking on the channel. In business and industrial systems, as many as 50 sets of users could share the same channel without having to listen to calls for each other's staffs. In government systems, users can avoid having to hear users outside their own agency. (Government channels are usually separated by distance between user groups. Only one local user group is assigned to a channel.)"

Nuff said

Bogget

But he said he tried it with with the same CTCSS and it didn't work.
How does a motorola radio somehow exclude itself from listening to other radios when they have the same ctcss/dcs?

When you have it in group mode how did you know what CTCSS it was on as it does not display it?
If It selects its own secret CTCSS?

I dont believe its XCTCSS as if this was available on this model it would be available in normal mode as well.

Bogget

I have no experience with these radios, but agree with Bogget that it sounds like a CTCSS/DCS selective call, possibly on a unique tone? I did read some Kenwoods have their own set of PLs. Can anyone decode the tone with a scanner? If nothing else it would eliminate the use of the common 50/112 CTCSS and DCS tones...

Did I read a post that another brand radio can hear the T8 but not talk back? That sounds like CTCSS/DCS to me, certainly if you can't hear any other form of selective calling tones or bursts.

And it's correct that 'Sub-channel 38' is meaningless between brands or even models of radio - Its the CTCSS Hz or DCS code that's needed to be known for compatibility, not what tone a manufacturer decides to assign to what 'Privacy Channel'

But I maybe be wrong... And this has made me want to have a better look at the T8s to find out!

it always baffled me as to what it was, it was a seperate setting to the normal pl and dpl codes as well.

The only thing I can think of is it may transmit a group code, from what I read as each handset can have an ID name and be a member of a group, Although there is a group setting called "ALL". so maybe it is looking for the group ID?
just an idea.
and I think the motorola has 38 ctcss tones where others may have less!

https://dl.dropboxusercontent.com/u/225 ... e%20EN.pdf
cheers Mark

Binatone Marina 900 does something similar to this with Group Call and Direct Call. You can even change the channel on all other radios in your group from one radio. I assume it uses something similar to DCS signalling to do this.

troffasky wrote:Binatone Marina 900 does something similar to this with Group Call and Direct Call. You can even change the channel on all other radios in your group from one radio. I assume it uses something similar to DCS signalling to do this.

i doubt its conventional ctcss/dcs but i cant confirm this

Yeah, that's why I said "something similar to", ie FSK digital data, at 134.4 bits per second.

Hi,

By process of elimination I have worked out the CCTS frequency to be 88.5 but it looks like I still ne to send an extra signal to get the recieveing handset to open up...

Any ideas? This should be simple but I'm banging my head against the wall. Google is not my friend on this no usful information pops up on the format of the handset/group ID which I believe is the missing info.

Thanks
Paul